Air conduit



Patented Feb. 15,1938 l 2,108,159 I UNITED STATES PATENT OFFICE l 2,108,159 e v f' Ala coNDUrr Waldemar J. Barman, Los Angeles, Calif.4 Application July 6, 1937, lSerial No. 152,228 8 Claims. (Cl. 13S-63) It is quite common practice to use air ducts In addition the fabric covering, especially after formed of various angular shapes for transmisbeing suitably painted, presents smooth surfaces sion of hot air for heating purposes, conditioned to which dust does not readily adhere and on air, and cooled air for air conditioning buildings upper horizontal surfaces dust may readilyl be 5 or for refrigeration. 'It has also been quite comremoved should it accumulate. In addition, un-

mon to heat insulate the angular ducts with a der conditions of the duct transmitting cold air, covering of fibrous material such as mineral Wool, there is but little condensation of moisture on so-called spun glass, asbestos fibers or the like, t the outside of the fabric and if in extreme cases wrapped around the ducts or conduits. However the moisture should collect, instead of soaking L many of such installations have been inefficient the insulating pad such moisture readily runs oif 10 in that the heat insulating material is not propthe fabric cover.

erly held in place on the conduit, that the cover- My invention is illustrated in connection \with ing is not uniform and particularly at the corthe accompanying drawing, irwhich: ners tendsto cut and separate sometimes leaving Fig. 1 is a perspective view of part of an anguthe corners of the conduit exposed. In addition lar shaped duct showing the manner of securing 15 when the conduits are covered with the mass or the fibrous insulatingcover, the angles and the pads of brous material, such material collects fabric outside covering.

dust and when the duct is used for transmitting Fig'. 2 is a longitudinal section and may be refrigerated air, despite the insulation, vmoisture considered as' taken on the longitudinal section sometimes condenses on the outside of the pads. line 2--2 ofiFig. 1 in the direction of the arrows. 20

An object and feature of my invention resides Fig. 3 is a transverse section and maybe conin part in providing corner protectors which also sidered as taken on the section line 3 3 of Fig. 1 function as spacing elements secured in position in the direction of the arrows. outside of the insulating covering and in align- Fig. 4 is an enlarged sectional view of one of 5 ment with the corners of the duct. These prothe corners of Fig. 3. tectors operate to hold the insulating pad in In the illustrationra duct is indicated by the proper position at the corners and also form numeral II. This is usually made of galvanized 'l straight line corners over which a covering of iron and may be considered as having four sides fabric such as canvas, duck or the like, may be I2,and angular corners I3. While the illustrastretched and stitched. Such fabric may then be tiony shows the duct as squarein cross `section, 30

painted or otherwise treated to partly shrink the these are frequently'made inl other rectangular fabric and thus form a tight drum-like and well shapes in accordance with the conditions for infitting covering. A further detail feature of my Vstallation. Alsothe ducts are sometimes made invention is the provision of corner angles formed with more than four angles. The heat insulating of sheet metal or equivalent material having the pad or covering I5 illustrated as of fibrous macorners project outwardly and the anges bent terial .such as mineral Wool has an outside prolaterally to conformsomewhat to the shape of the tecting cover I6 usually of water proof paper. insulating covering at the corners of the duct.- Such pads are .usually received from the manu- Thesc spacing corner angles are preferably some'- facturer made up in' long lengths or rolls and of cover stretched from corner to corner. lIn order sulating material and the paper covering adhere to secure the angles and the fabric covering, this one to the other or sometimes the fibrous matecovering is preferably bound in place by a helical rial is attached to the paper by glue or cement. winding of wire or Wire rings bound around the Thus the pad with the paper may be lapped outside of the fibrous insulation. Then the angles around the duct usually with a slight overlap at may be secured to the Wire wrapping by short the joint. The fibrous covering withthe paper is pieces of twisted Wire engaging through perforathen secured in place by a wrapping of Wire II. tions in the flanges of the angle and attached to This may be a long wire wrapped in a helical the wrapping wire. Another characteristic of my manner with the adjacent loops ofthe wire ap- .'.9 what bulbous at lthe angle and have the fabric various specified widths in which the fibrous in- 40 invention resides in forming air spaces inside of proximately the same distance apart. However, 50

the fabric covering and between such covering sometimes the wire wrapping is made in the form and the corner angles and the insulating pad on of individual loops with the ends twisted together. each side of the duct between the corners, thus This causes the .insulating packing to be someadding to the heat insulating characteristics of what compressed outside of the corners as indil a duct covered in'accordance with my invention. cated at I8 and permits some bulge as indicated 55 at I9 between the corners. The wrapping of wire is not made sufficiently tight to press the paper covering I6 into the corners I3 of the duct and hence as the wire has a certain amount of slackness, it bows outwardly between the corners permitting the bulge or thicker sections of the fibrous insulation.

After a duct has been coveredv with the fibrous heat insulating material as above described, protecting and spacing corner angles 25 are positioned outside and in alignment with each corner of the duct. These are preferably formed of sheet metal with a reverse corner bend 26 formed somewhat bulbous, this leaving a slight space 21 immediately inside. the corner whichV may if desired, have a Wire extending longitudinally. There are diverging flanges 28, these preferably having a concave bend outwardly as indicated at 29 and have the edge parts 30 diverging. The divergence is made to conform somewhat to the corners I3 but even when such corners are a right angle, it is preferable to have the angle between the end parts 3D forming an acute angle slightly less than a right angle. Each flange of an angle has a series of perforations 3I spaced along its length and a binding wire 3| is fitted in each perforation and around an adjacent section of the wrapping wire I1 and secured by a twist indicated at 32 or in other suitable manner. By thisccnstruction the angles 25 are securely attached to the wrapping of the fibrous heat insulation and held directly with the corners I3 and the reverse bend 26 of the angles in alignment.

Usually the ducts are made up in definite lengths, each length having outwardly turned flanges 35 and adjacent duct section secured together atsuch flanges. In this case the angles 25 have their flanges engaging the flanges of the duct as indicated at 36. It may be necessary to bend the flanges 28 and the marginal edges 30 slightly outwardly to conform to the right angle of adjacent flanges 35. Such flanges therefore also are operative to hold the angles 25 at a fixed distance from the corners I3.

A fabric outside cover 4D is stretched over the angles 25, such fabric having Icorners 4I and webs l2 extending between contiguous corners. Each web forms a plane, thev fabric cover is usually stitched with a concealed sailmakers stitching; the fabric being stretched to form, a reasonably tight cover. The angles 25 should be so positioned that the bulge I9 does not press the web of the v fabric outwardly. However the tightly stretched between the angles 25.

fabric is operative to 'limit the amount of the bulge I9 of the fibrous heat insulating material. It will be seen therefore that there are a series of air spaces 43 inside of the fabric between the corner angles 25 and the paper wrapping I6 which increases the heat insulating characteristics of the covered conduits. This fabric may be coated with a suitable paint or so-called dope which has the characteristics of somewhat shrinking the fabric such as canvas or duck and there# fore forms somewhat tight drum-lik-e surfaces Thus the completely covered duct has not only a neat appearance but has surfaces which do not readily accumulate mission of air or the like having angular corners and a covering of heat insulation combined with rigid angle devices secured outside of the insulating cover in alignment with the angular corners of the duct and an outside covering of fabric or the like stretched over said angle devices.

2. In a device as described, in which a duct having angular corners and adapted for transmission of air has a heat insulating covering of fibrous material combined with spacing elements each formed of a rigid angle member with diverging anges, the anges engaging the outside of the insulating covering with the angles in alignment with the corners of the duct and an outside covering of fabric or the like stretched over and between the various angles and enclosing the heat insulating covering.

3. In a device as described, in which a duct having angular corners adapted. for transmission of air or' the like has a heat insulating covering of brous material in contact with the sides of the duct and extending around the corners of such duct combined'with a wire wrapping on the outside of the heat insulating material, a spacing device formed of an angle having diverging flanges positioned with the flanges engaging the outside of the covering and in alignment with each corner of the duct, means attaching each angle device to the wrapping wire and an outside covering of fabric or the like extending over the outside angle of each spacing device and stretched'between adjacent spacing devices substantially parallel to the varioussides of the duct, the said outside covering confining the heat insulating material and forming air spaces between the outside covering and the outside of the heat insulating material.

4. In a device as described, in which a duct formed of sheet material has a plurality of corners and a covering of fibrous heat insulating material extending completely around the ductv and confined by a protectivecover and combined -with a Wrapping of wire around such protecting cover, the wire binding the insulating material and the cover on the sides and the corners of the duct and spacing devices formed of angles with diverging flanges', the flanges contacting the wire and the protecting cover, means to secure the flanges to the wire and an outside cover of fabric or the like stretched over the outside of the 'said angles and forming substantially plane surfaces between adjacent angles, the said outside cover forming with the protecting covering a series of air spaces.

5. In a device as described and claimed in claim 4, the duct having transverse outwardly extending flanges, the corner angles engaging such flanges, the flanges of the duct being operative to space the corner flanges from th'e duct.

6. In a device as described in which a duct formed of sheet material has a series of flat surfaces and a plurality of corners, a covering of heat rinsulating material extending completely around the duct, a wrapping means securing the material to the duct, the material forming a thicker covering on the sides between the corners than at the corners, a spacing angle in alignment with each corner, each having a pair of diverging flanges ypositioned contiguous to the covering opposite a corner and an outside covering of fabric or the like stretched over the outside of the angles and forming substantially plane surfacesbetween adjacent angles and being positioned outside of the insulating covering.

7. In a device as described and claimed in sov wardly turned ilanges, a covering of insulating material on the at surfaces and the outside of the corners, an angle positioned outside of each corner and having diverging flanges, the flanges of the angles engaging the anges ofthe duct and an outside wrapping of fabric or the like stretched over the angles and forming substantially plane surfaces between adjacent angles.

ALDEMAR J. BARMAN. 

